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Base A99 Height question
- Thread starter Joe 610
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- a99 antenna height
Antron 99 at 10' AGL reaching out 20 miles? You're quite lucky. You've got to get that omni-directional up at least 1/2 λ height AGL. A full wavelength height will prove unbelievably better. At full λ height your fat tire donut primary radiation lobe maximum would be much greater on the horizon; instead of your maximum energy being wasted on the stars. You want it above all the immediate area obstructions. And your ground? A GPKit will prove to be a big help at an affordable cost compared to the alternative ground plane.
While I'm blathering on I've a bit of insight on that 8' ground rod. For your edification, driving that 8'er into the ground at a significant angle is far better than straight down through dry ground. Better chance of passing through moist ground portions under the surface when driven at an angle.
Remember a monopole alone is 1/2 of a complete antenna, a dipole. Think of a magnet mounted mobile antenna. That 1/4λ antenna is 1/2 of a complete antenna, like the A99, the other 1/2 is the automobile it's mounted on, is its ground plane.
I operate a Imax 2000, with GPK, whipping the winds at 25' and have done so for nearly 20 years. My Sirio SD27, another vertical omnidirectional antenna, does not perform as well as the Imax. My Sirio SY-3 is not yet up to its intended 36' operating height. The SD27 and SY-3 are both affordable and strongly made, The SY-3 is a 10#, 3 element Yagi. Sirio antennas are widely employed in the EU.vertical omnidirectional antenna
The 5/8 λ antenna, Sirio Tornado, Imax 2000, have a remarkable radiation pattern over the 1/2 λ monopole. The Tornado is worth a 2nd look over the Imax, for sake of price. Certainly worth consideration. The 5/8 λ primary lobe is reaching out towards the horizon significantly more so. Think motorcycle tire over fat off-road truck tyre. That wattage not wasted beaming towards the stars is directed toward the horizon. And by adding height to the feed point you lower the angle towards and above the horizon.
While I'm blathering on I've a bit of insight on that 8' ground rod. For your edification, driving that 8'er into the ground at a significant angle is far better than straight down through dry ground. Better chance of passing through moist ground portions under the surface when driven at an angle.
Remember a monopole alone is 1/2 of a complete antenna, a dipole. Think of a magnet mounted mobile antenna. That 1/4λ antenna is 1/2 of a complete antenna, like the A99, the other 1/2 is the automobile it's mounted on, is its ground plane.
I operate a Imax 2000, with GPK, whipping the winds at 25' and have done so for nearly 20 years. My Sirio SD27, another vertical omnidirectional antenna, does not perform as well as the Imax. My Sirio SY-3 is not yet up to its intended 36' operating height. The SD27 and SY-3 are both affordable and strongly made, The SY-3 is a 10#, 3 element Yagi. Sirio antennas are widely employed in the EU.vertical omnidirectional antenna
The 5/8 λ antenna, Sirio Tornado, Imax 2000, have a remarkable radiation pattern over the 1/2 λ monopole. The Tornado is worth a 2nd look over the Imax, for sake of price. Certainly worth consideration. The 5/8 λ primary lobe is reaching out towards the horizon significantly more so. Think motorcycle tire over fat off-road truck tyre. That wattage not wasted beaming towards the stars is directed toward the horizon. And by adding height to the feed point you lower the angle towards and above the horizon.
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You did say you are "blathering" here so...
I would like to know where you got this idea, I've not heard anyone say this before.
Also, for anyone subject to inspections, I highly recommend checking the National Electric Code 250.53(G) (in the states, or whatever is used where you live) and go by that...
Significant? Lets model it and see...
Here is a model comparing a 1/2 wavelength antenna and a 5/8 wavelength antenna mounted at 25 feet. The difference in angle of radiation is 1 degree. The difference in gain is 0.29 dB. I don't see either of those as being significant. Further, the higher the antennas are mounted the smaller the difference between them both for the angle of radiation and the gain.
On the plus side for the 5/8, it is more efficient, however, most of that efficiency gain is being lost as most of the extra gain you would get from being more efficient is...
The DB
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Sorry Joe 610 for the hi-jacking. But this could be educational.
Thank you DB for your pictures worth a thousand words. Grounding Option 2, having a 45d angle is just as was suggested. Yes, it impotent not to interfere with the grounding network of your dwelling. As surely would be the case of the alternative grounding grid often employed by HAMers with perhaps dozens of buried grounding wires, jutting out from their garage based HAM "shack", totally destroying that carefully modeled ground rod placement. And don't forget to shell out those taxes to your local goobermint inspector to insure your antenna grounding is up to code.
What is it DB you have an itch to dispel the validity of 5/8 λ over 1/2 wavelength. I got pictures! xCept I'm hamstrung currently with a POS backup Apple laptop whereas them pictures are on the WinDoze confuser with failing video card. But no sweat, there are enough pics on the internet to see the validity of 5/8 over 1/2 wavelength.
Antenna modeling ain't what it used to be. I'll be quacked if Red isn't Blue and Blue isn't Red. I swear it's bass ackwards in my recall. And where is all that additional 2ndary moonshot groundwave lobe energy represented in Blue not shown in Red; it should be shooting out like a Corn Husker hard on driving to the goal post; except it would be Blue.
0.29 DBi? Inasmuch as dbd gain of .29 can be viewed as significant by perhaps 20%. FYI the A99 is marketed as 9.9 DBi gain. And since we're comparing apples and oranges I might add the Imax 2000 boasts an additional 2 Dbi over the A99 or 72" in the real world. If the A99 has an imaginary 9.9DBi and the Imax is 11.9 DBi (I recall 12.5DBi gain but settle for +2) where is that additional 5/8 λ (2DBi) energy emanating toward in modeled pics. Is the selected 25' height that which created the ground lobe?
DB, if you have the time and inclination, model again at 1/2λ and again at 1 full λ heights, since they were parameters in my blathering. I'm curious to see how the 5/8λ ground lobe is represented.
Yes there is a point of diminishing returns with antenna heights, just shy of 2 λ height the DBi gain is no longer increasing; in fact likely diminishing. In my recall, above 1 λ height a lowering angle on the horizon is negligible, if at all. Also above 1 λ the groundwave lobes increase exponentially; well not quite that bad. But energy wasted is wasted. When yer speaking dipole it's a terrible waste.
Thank you DB for your pictures worth a thousand words. Grounding Option 2, having a 45d angle is just as was suggested. Yes, it impotent not to interfere with the grounding network of your dwelling. As surely would be the case of the alternative grounding grid often employed by HAMers with perhaps dozens of buried grounding wires, jutting out from their garage based HAM "shack", totally destroying that carefully modeled ground rod placement. And don't forget to shell out those taxes to your local goobermint inspector to insure your antenna grounding is up to code.
What is it DB you have an itch to dispel the validity of 5/8 λ over 1/2 wavelength. I got pictures! xCept I'm hamstrung currently with a POS backup Apple laptop whereas them pictures are on the WinDoze confuser with failing video card. But no sweat, there are enough pics on the internet to see the validity of 5/8 over 1/2 wavelength.
Antenna modeling ain't what it used to be. I'll be quacked if Red isn't Blue and Blue isn't Red. I swear it's bass ackwards in my recall. And where is all that additional 2ndary moonshot groundwave lobe energy represented in Blue not shown in Red; it should be shooting out like a Corn Husker hard on driving to the goal post; except it would be Blue.
0.29 DBi? Inasmuch as dbd gain of .29 can be viewed as significant by perhaps 20%. FYI the A99 is marketed as 9.9 DBi gain. And since we're comparing apples and oranges I might add the Imax 2000 boasts an additional 2 Dbi over the A99 or 72" in the real world. If the A99 has an imaginary 9.9DBi and the Imax is 11.9 DBi (I recall 12.5DBi gain but settle for +2) where is that additional 5/8 λ (2DBi) energy emanating toward in modeled pics. Is the selected 25' height that which created the ground lobe?
DB, if you have the time and inclination, model again at 1/2λ and again at 1 full λ heights, since they were parameters in my blathering. I'm curious to see how the 5/8λ ground lobe is represented.
Yes there is a point of diminishing returns with antenna heights, just shy of 2 λ height the DBi gain is no longer increasing; in fact likely diminishing. In my recall, above 1 λ height a lowering angle on the horizon is negligible, if at all. Also above 1 λ the groundwave lobes increase exponentially; well not quite that bad. But energy wasted is wasted. When yer speaking dipole it's a terrible waste.
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Grounding option 2, for use when bedrock won't let you put the ground rod in straight down. In such a case, you want to put the 8 foot ground rod in as straight as possible, and still approaches bedrock. If bedrock is at least 8 feet below where the ground rod is placed there is no need to angle it and doing so can get you in trouble.
I'm simply interested in the truth, which goes far deeper than the "general knowledge" of the ham and CB communities. Many people think that there is a world of difference between the two lengths, but when replacing one with the other in the real world, and noticing a big difference, its typically because you had a problem to begin with. Sure, in a perfect, theoretical environment, I can show a huge difference between these two antennas, but the closer the model gets to the real world the smaller said difference becomes.
Lol, funny. Typically, I find that people who say things like this don't understand modeling as much as they thing they do. Its also funny when this is said as we are also using the same programs from the time of "used to be", whenever that may have been.
I see, so you don't understand decibels either, instead implying dBi or dBd when neither is present or necessary. And 0.29 dB gain is not 20%, its closer to 7%, actually just under...
I have, multiple times in fact... Sure, why not, its only changing one parameter in already existing models...
Oh look, even less of a difference now... Oh wait, I said something to this effect already...
Yep, height has that effect as well, as you add more height, the existing lobes get compressed down lower and lower as more and more new lobes form. This is something that no one ever seems to consider when dealing with antenna height. every half of a wavelength adds an additional lobe in the pattern, which in effect takes power away from all other existing lobes. The odd thing about the 5/8 wavelength compared to the 1/2 wavelength design is the lobes simply form earlier, and a second high angle lobe exists even if the antenna is mounted at ground level. At very low heights this gives an advantage to the lower angle lobe, but that advantage effectively disappears at less than 1/2 wavelength in height.
In actuality, if you take a half wavelength and mount it at the same tip height as the 5/8 wavelength antenna, the differences between them all but dissappears, and in most real world cases the 1/2 wavelength antenna at said tip height actually outperforms the 5/8 wavelength antenna when it comes to local contacts. This tells us that the difference between 1/2 and 5/8 wavelength antennas has more to do with the tip heights of the antennas over the actual length of said antennas. Modeling has actually explained why this is, but you will have to go dig up those posts if you are interested (somehow I doubt you care).
And you measured this how? Please please humor me and say s-meter. Please I beg you... or did you blindly believe their documentation? That would be even better.
Actually, I can get the a99 to show a 9.9 dBi gain in an antenna model, and I could get the Imax to show a 2 dB higher gain that that. It is possible to do, and an experienced modeler such as myself wouldn't even need to use various tricks to manipulate the output of said models to do it. No one would ever set these antennas up in the way that they would be modeled to get said results, which makes the models useless, but it can and has been done.
I agree with this, for the most part. Diminishing returns add up quickly, and is in fact increase exponentially as you add more height. I've shown this with models in the past. One to two wavelengths seems to be the maximum effective heights for DX patterns, and I would say pattern wise, one wavelength is better than two in most cases. If you are trying for local contacts, three wavelengths of height isn't out of the equation if you can afford it. That is another thing with height, cost goes up exponentially with more height. In the models, you don't start loosing gain until more like ten wavelengths, although this isn't factoring in the curvature of the earth, so it is less than that to some extent...
Ground wave lobes? Are you assuming the low angle lobes in the models above have anything to do with ground wave propagation?
When it comes to DX, in my experience, a half wavelength antenna mounted at 25 feet or so seems to work the best for me, even beating out 5/8 wavelength antennas at the same height. However, your mileage may vary as every install location is different. When it comes to local contacts, well, I already talked about that above, and my experience no matter where said antennas are installed hold to that.
The DB
Ok my friend let us agree to disagree.
My education in the realm of Radio is as a stumbling bumbling idiot in comparison to your own. I can only go upon my existing education to which you've added.
I submit the following fodder:
My Acer Windoze confuser rebounded from it's video card dilemma and I retrieved a few .ODT files.
Additionally: 10M Antenna Height and Gain
Based on 100 watt radio transmitted power.
I. At .5 wavelength (17.5481 feet) gain should be 13.15 dBi = 1259.378 watts ERP. with a radiation angle of 24 degrees.
II. At 1 wavelength (35.0962 feet) gain should be 14.62 dBi = 1766.673 watts ERP and a radiation angle of 15 degrees.
III. At 1.5 wavelength (52.6443 feet) gain should be 15.12 dBi = 1982.240 watts ERP and a radiation angle of 9 degrees.
IV. At 2 wavelengths (70.1924 feet) gain should be 15.09 dBi = 1968.594 watts ERP and a radiation angle of 6 degrees.
Note of importance is the diminished gain and ERP as antenna height moves higher than 1.5λ.
500W 10.64dBi ERP 3532
EIRP 5793
Effective Isotropic Radiated Power (EIRP) is the apparent power transmitted towards the receiver from omni-directional antenna; non-specific.
Footnote 07.30.22 The calculations above were based on, if I recall correctly, a Imax 2000 DBi of 12.5; your results may vary based on wishful thinking or real world fact. Advertised DBi is all I can go on; that and reeducation. Thanks DB for your attendance.
To my amazement I read of the huge increases related to the values of Db gain.
Simply said a 10DBi gain is a 10-fold gain and jumps amazingly to 20-fold a mere 3DBi higher (13DBi). Nawh, I sez to myself, Shirley that is a lie.
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The SR655 is a good radio, if you don't screw with it you should be getting 75W or better. I've seen peaked units pushing 90W+. 75W will get you out a fairly good distance, IF your have feed point is high enough. I have a 655, at the repair shop, having the entire front face replaced. When the meter fogs over, mine did and I've no idea why, its not just a matter of replacing the meter. The Freq/Channel selector was a piece of crap as it is on my SR955 w/SSB, the only difference, I have both. The 955 had the control knob mechanism replaced once, with the same crap designed mechanism. I'm told the newer units have a better switching mechanism and my repaired 655 unit will be toting one.
Of course more power is good, but operate with reserve is my moto.
As has been said and again, height is might; but, only up to a point. The point of diminishing returns.
Where along the antenna is the signal received and power emitted? To my knowledge, on transmit the base of the antenna has the hotter power and peters out with length. That doesn't mean you can take a hold of the end of an inverted Vee on full power transmit and not get a groin pull. On receive it's the entire antenna is at work. The incoming signal clips your antenna that's the level of your receive.
Bottom line, antenna/feed point height > 1/2 wavelength, minimum. I'll wage $1 to a dog nasty when you get your antenna up on an 18' mast that missing local "ish" friend will be back in full.
Fair enough, at least for the ground rod discussion I will agree with this, with the caveat that if there are codes in your area and you are subject to inspection, follow the codes so you don't get dinged, which was the only real point I was trying to make in the first place. Aside from that, do what you want. I don't see putting an 8 foot ground rod at a 45 degree angle having any real effect on your antenna system in any way as in most cases, for the CB band, a four foot ground rod is plenty as far as the RF is concerned. That being said, I wouldn't use just a four foot ground rod for things like electrical or lightening grounds...
The rest of Alabama Buckeye's post (number 81) above I am going to respond to in a different thread. We are hijacking this thread with this conversation, and there are things that I want to address.
This question was asked? I looked again through the entire thread and didn't see it anywhere... The correct answer for the CB band is between 8.5 and 9 feet down from the tip of the antenna, although there are some exceptions. Unfortunately there is no real easy explanation, but is has to do with the current distribution of the antenna itself. If someone wants I will try and come up with an easier to understand explanation.
The DB
A little update on my A99. I ordered a Sirio 2016 this morning haha. Will be here Thursday and I can’t wait.
The Antron 99 works best at a full wave length, which is about 36 feet from the ground to the base of the antenna, i have mine set up that way and talk skip from the west coast to the east coast, also talk to Hawaii, New Zealand, The Virgin Islands, and a couple of other countries.
It proves only band conditions not antenna performance.
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SP5IT is correct.
It is hard to judge performance of an antenna based on Skip.
I have worked half the US on a 23 channel Midland and a mag mount on a trailer when the band is open.
73
Jeff
yep dang walkie talkie can go far at right condition. when signals are weak,you hear and contac them and they are over 40 miles away in non skip times then we can judge antennas